Collapsible corrugated plastic box

ABSTRACT

This invention provides a collapsible box made of corrugated plastic, which has improved hinge line/score line configurations between walls and panels and improved hand holds. A plastic box of this invention preferably has an automatically lockable bottom to facilitate erection of the box, and can be easily collapsed for return shipment and reuse.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to collapsible boxes and more particularlya collapsible box made of corrugated plastic.

[0003] 2. Description of the Prior Art

[0004] Collapsible corrugated boxes and cartons made of paperboard arewell known in the art. Such boxes and cartons typically include verticalside walls and top and bottom flaps on the side walls for forming abottom end wall and a top closure for the box. The paperboard is crushedalong lines between adjacent side walls and between the side walls andthe flaps to form “score lines” or hinge lines for bending thepaperboard.

[0005] It is known to provide a foldable carton having hinged togetherbottom panels for automatically forming the carton bottom when thecarton is erected. Cartons having such automatically forming bottoms aredisclosed in U.S. Pat. Nos. 2,327,709 and 4,289,268.

[0006] It is also known to provide a plastic box as is disclosed in U.S.Pat. No. 4,948,039. That patent discloses a container made out of flutedplastic having integral hinges between the walls and flaps and havingVelcro® strips for fastening the walls and panels together. The hingesin the container are made by cutting one facing sheet in the flutedplastic and hinging the walls and flaps on the other (uncut) facingsheet. The container disclosed in that patent is said to be easilycollapsible and reusable.

[0007] There is a need for an improved collapsible box made ofcorrugated plastic that is economical and suitable for high speedmanufacture and erection. An improved plastic carton is needed that ismore durable and resistant to tearing. A plastic box is needed that willset up better when erected and not collapse on itself. A corrugatedplastic carton is needed that includes an automatically lockable bottomand a plastic box that can be reused many times.

SUMMARY OF THE INVENTION

[0008] This invention satisfies the needs for an economical plastic boxthat can be manufactured using high speed equipment and which is durableand capable of being reused many times.

[0009] This invention provides a collapsible box made of corrugatedplastic, which has improved hinge/score line configurations betweenwalls and panels and improved hand holds. A plastic box of thisinvention preferably has an automatically lockable bottom to facilitateerection of the box, and can be easily collapsed for return shipment andreuse.

[0010] A collapsible box of this invention may have offset scoring forthe bottom flaps so the box sets up better. Offset scoring produces abox with less memory when erected, so the box stays erected withoutcollapsing on itself.

[0011] The score lines in a box of this invention preferably terminateshort of slots cut between panels and flaps so the corrugated plasticwill have increased resistance to tearing. The box also preferably hashand holds defined by cut lines that terminate in rounded corners, whichalso reduce risk of tearing the plastic.

[0012] Accordingly, an object of this invention is to provide animproved collapsible box made of corrugated plastic.

[0013] The above and other objects and advantages of this invention willbe more fully understood and appreciated by reference to the followingdescription and the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 is a perspective view of a collapsible box of the typesuitable for use with this invention.

[0015]FIG. 2 is a fragmentary cross-section through corrugated plasticfor use in a box of this invention.

[0016]FIG. 3 is a plan view of a pattern or blank for a box having acollapsible lockable bottom suitable for use in this invention.

[0017]FIG. 4 is a bottom view of an erected box showing the lockedbottom flaps.

[0018]FIG. 5 is a fragmentary view showing an offset score in acollapsible box of this invention.

[0019]FIG. 6 is a fragmentary cross-section through a hinge score ofthis invention before the corrugated plastic is folded at the score.

[0020]FIG. 7 is a fragmentary cross-section through a hinge score ofthis invention showing the corrugated plastic folded at the score.

[0021]FIG. 8 is a fragmentary view showing a diagonal score in acollapsible box of this invention.

[0022]FIG. 9 is a fragmentary view of a top corner of a box of thisinvention showing the score lines at the corner intersection of the sidewalls and top flaps.

[0023]FIG. 10 is a fragmentary side elevation of a vertical width wallof a box of this invention showing a hand hold in the width wall.

[0024]FIG. 11 is a fragmentary cross-section through an alternativecorrugated plastic that can be used in the practice of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025]FIG. 1 illustrates a collapsible box 10 that is suitable for useof the present invention. The box 10 is preferably rectangular or squarein footprint but may also have hexagonal or other configurations. Thebox has a pair of vertical width walls 12, a pair of vertical lengthwalls 14, and a bottom closure 20 as is described below. The boxoptionally includes a pair of top width wall flaps 16 and a pair of toplength wall flaps 18; it can also be in the form of a half slottedcontainer, which does not include top flaps.

[0026] The box 10 has vertical hinge lines 22 between the width walls 12and length walls 14, hinge lines 24 between the width walls 12 and widthwall flap 16, and hinge lines 26 between the length walls 14 and lengthwall flaps 18. The box also has hinge lines between the width walls 12,length walls 14 and bottom end wall flaps as is described below.

[0027] All score lines in the box 10 facilitate erecting and collapsingthe box. In accordance with this invention, a box 10 may have uniquehinge line/score line configurations which improve the performance anddurability of the box.

[0028] Box 10 may also include hand holds 28 in opposite width walls 12.The hand holds 28 are defined by a cut line 30 completely through thebox material and may have a hinge/score line 32 at the top of each handhold as is described below in more detail.

[0029] The top width flaps 16 may have hinge/score lines 34 across themfor forming a bend at the line, and the top length wall flaps may haveL-shaped flaps 36 in them for providing slots to receive corners of thewidth flaps when the box 10 is closed by downward folding of the flaps16, 18. Each L-shaped flap 36 may be defined by a cut line 38 and ahinge/score line 40 so the flap can be hinged into the box to permitinsertion of the corners of flaps 16. The second flaps 36 provide a skiso the flaps can be inserted into the box without damaging the contentsof the box.

[0030] A box 10 of this invention may be made of corrugated sheetplastic material 41 such as that shown in FIG. 2. Corrugated plastic 41is well known material, but has received only limited application incollapsible boxes (see U.S. Pat. No. 4,948,039). Corrugated plastic 41has parallel facing sheets 42, 44 and spaced, integral interconnectingribs 46 between the facing sheets. The plastic sheet material 41 can beeasily extruded from a variety of plastic resins such as polyethylene,polypropylene, and the like. A box of this invention may also be made ofconical plastic sheet material 80 such as that shown in FIG. 11, whichincludes facing sheets 81, 82 bonded to a corrugated intermediate sheet83 as for example by melt bonding, ultrasonic bonding or an adhesive.

[0031]FIG. 3 shows a blank 48 for a preferred embodiment of a box 10 ofthis invention. The blank includes panels which form the width walls 12,length walls 14, top width flaps 16, top length flaps 18, bottom widthflaps 50, bottom length flaps 52, 54 and glue flap 56. Score/hinge linesare also provided in the blank 48. These score lines may include scoreline 22 between the width walls 12 and length walls 16, score lines 24between the width walls 12 and length wall flaps 16, score lines 26between the length walls 14 and length wall flaps 16, scores 58 betweenthe width walls 12 and bottom end wall flaps 50, score lines 60 betweenthe length walls 14 and the length wall flaps 52, 54, score lines 60 inthe top width wall flaps 16, and score lines 62 in the bottom end wallflaps 50. The blank 48 also preferably has hand holds 28 in the widthwalls 12. The score lines 62 in each of the bottom width wall flaps 50bisect the corner where the width wall flaps meet the bottom length wallflap 52, 54, length wall 14 and width wall 12, and defines a tab portion64, which is to be adhesively bonded to the adjacent length flap to formthe automatically lockable bottom closure for a box made from the blank48.

[0032] Manufacture of a box 10 from the blank 48 is effected by shapingthe blank into its box shape and gluing or otherwise connecting glueflap 56 to the exterior surface of length wall 14. The bottom flaps 50,52, 54 are folded into a bottom closure, with flap 54 being foldedfirst, followed by flap 52 and then flaps 50. Adhesive or glue haspreferably been applied to the interface between tabs 64 and flaps 52,54 to adhesively bond the tabs to the flaps at 66 as shown in FIG. 4.Alternatively, the tabs 64 can be joined or connected to flaps 52, 54 byultrasonic welding or a hook and loop closure.

[0033] In accordance with this invention, the hinge lines between theside walls 12, 14 and the bottom end flaps 50, 52, 54 of a box arepreferably vertically offset as is shown in FIG. 5. Such hinge linespreferably are formed by a crushed score line 68 and a perforated scoreline 70 parallel to the crushed score line. The two score lines 68, 70may be spaced apart approximately one to two times the thickness of thecorrugated plastic sheet material. The crushed score line 68 is formedby well known techniques in which a score tool or indenter is pressedagainst one face 42 of the corrugated material to collapse or crush theconnecting ribs 46 in the material (FIG. 6). The perforated score 72 isa line of perforations cut through one facing sheet of the corrugatedplastic. The crushed score 68 is preferably on the inside face (towardinside of box) of the plastic, and the perforations in the perforatedscore are preferably through the exterior face of the plastic, and theperforated score 70 is preferably the upper score in the hinge line.However, such locations of the scores are not critical to the invention.

[0034]FIG. 6 shows the parallel scores 68, 70 which form a hinge line ofthis invention, before the plastic 41 is folded or hinged, and FIG. 7shows the plastic after it has been folded. The weaker perforated score70 is designed to fold first and provide the desired dimensional controlin the manufacture of the box. The crushed score 68 provides anotherbend point for the flap so each score has to accommodate only 90° offolding. This double hinged score enables the flaps to fold more easilyand accurately as compared to a single score.

[0035] The vertically offset, horizontal scores 68, 70 at the bottom ofadjacent walls 12 and 14 as seen in FIGS. 5, 6 and 7 provide morestability to a box of this invention. A box having such an offset scoresets up better and has less memory when erected. The reduction in memoryenables the box to stay erected without collapsing on itself. The bottomfull overlap flap 54 (FIG. 3) also tends to lay more flat in boxes withoffset scores, which is beneficial when filling the box with lightweight products like potato chips.

[0036]FIG. 8 shows diagonal hinge/score lines that may be used as analternative to the offset scores of FIG. 5. In the embodiment of FIG. 8,the score lines 72, 74 are parallel to each other, but extend diagonallyor at an angle (about 5-10°) to the score line 22 between the walls 12,14. This alternative is more typically used when the bottom or topclosure on the box has panels adapted to be closed and interlocked by aconventional French fold, instead of an automatically locking bottomclosure as illustrated in FIGS. 1 and 3. The purpose of the horizontallyrunning diagonal scoring is to alleviate the stress and memory involvedwhen all the scoring is on the same plane when mechanically interlockingthe top or bottom flaps, commonly known as French Folding the box. Ifthe scores run on the same plane, the flaps do not lay flat wheninterlocked; they bow outwardly a great deal. This is partially causedby the material being on the same plane and trying to occupy the samespace, when in reality, one flap need to be a little lower(approximately the thickness of the material being folded) than theadjacent interlocking flap. In order for the flaps to lock together, oneach flap, half is above the adjacent panel on one side, and tuckedunderneath the adjacent panel on the opposite side. Therefore, the scoreneeds to not run parallel to the floor, but diagonally to accommodatethe flap being higher on one end than the other. The diagonal scoringallows the flaps to lay flatter when engaged and helps minimize thepossibility of a load tipping due to the flaps bowing too much usingconventional scoring.

[0037]FIG. 9 shows additional features of the bend/score lines in a boxof this invention. As seen in this figure, the score lines 22, 24, 26,34 between the walls 12, 14 and flaps 16, 18 terminate short of theedges of the flaps and short of the slots cut between panels. Forexample, hinge/score line 34 in flap 16 and hinge/score lines 24, 26between walls 12, 14 and panels 16, 18 terminate approximately ½-1½inches and preferably 1 inch (1″) short of the edges of the flaps 16,18. Terminating the scores short of the flaps helps reduce weak pointsthat could start a tear. Tears tend to propagate in plastic once a tearhas started. Accordingly, prior art boxes having scores that extend intothe slots between flaps are much more susceptible to tearing than areboxes of this invention.

[0038] The vertical hinge/score lines 22 also terminate short of theslot 17 between flaps 16 and 18. A gap of unscored plastic approximately½ inch long is left at the end of each vertical score. This helps reduceweak points that could be the start of a tear in the plastic.

[0039]FIG. 10 shows a hand hold in a vertical width panel 12. The handhold is formed by a cut line 30 across the bottom and up both sides ofthe hand hold to define a flap 29 of plastic in the hand hold. Itfurther includes a score line 32 across the top of the hand hold 28which facilitates hinging of the flap 29 of plastic. The score line 32can be either a crushed score or a perforated score and may be in eitherthe inside or outside facing sheet in the plastic. However, the scoreline 32 is preferably a crushed score on the inside face of the plastic.In accordance with this invention, the cut line 30 ends in a radius orrounded corner 76 at the top of the hand hold 28 on both sides of thehand hold. The rounded corners 76 move the stress point in the plasticaway from the top end of the vertical sides of the hand hold 28 andspreads the stress point to reduce risk of tearing the plastic duringlifting of a box of this invention. Conventional hand holds, which donot include rounded corners and which end parallel to the flute lines,tend to tear easily. The rounded corners 76 of the preferred embodimentshown in FIG. 10 spread the load across the score line 32.

[0040] It is therefore seen that this invention provides an improvedcollapsible box made of corrugated plastic that can be manufactured andassembled economically by high speed equipment. The box is moreconvenient to use and also more durable than prior art boxes. It will beapparent to those skilled in the art that numerous modifications can bemade to the preferred embodiments selected for illustration withoutdeparting from the invention or the scope of the claims appended hereto.For example, hook and loop fasteners, such as those made under the tradedesignation Velcro® by the Velcro Company, could be used to effectclosure of the top and/or bottom of the box.

What is claimed is:
 1. A collapsible box made of corrugated plasticcomprising at least four vertical side walls and a bottom end flapintegrally connected to each of said side walls through a hinge line,wherein the hinge line between adjacent side walls and their respectivebottom end walls are vertically offset.
 2. A collapsible box as setforth in claim 1 in which each of said hinge lines between each saidside wall and its respective end flap comprises a crushed score line anda perforated score line substantially parallel to said crushed scoreline.
 3. A collapsible box as set forth in claim 1 which has at leastone hand hold cut into a said side wall of the box, said hand holdcomprising a cut line through said corrugated plastic to define a hingedflap in the side wall with said cut line on both sides and the bottom ofsaid flap and ending in a rounded corner at the top of each side of saidflap.
 4. A collapsible box as set forth in claim 1 that includes a topend flap connected to each said side wall through a hinge line.
 5. Acollapsible box as set forth in claim 4 which includes slots cut betweenadjacent top flaps and adjacent bottom flaps, and crushed vertical scorelines between adjacent side walls with each of said vertical score linesterminating short of said slots.
 6. A collapsible box as set forth inclaim 5 in which said vertical score lines terminate approximately ½inch short of each slot.
 7. A collapsible box as set forth in claim 1 inwhich said hinge lines between said top flaps and said side wallsterminate short of the edges of the side walls and top flaps.
 8. Acollapsible box as set forth in claim 7 in which said hinge linesbetween said top flaps and said side walls terminate approximately 1inch short of the edges of the side walls and top flaps.
 9. Acollapsible box as set forth in claim 1 which is rectangular inhorizontal section with four said vertical side walls including twolength walls and two width walls, and said hinge line between said twowidth walls and their bottom end flaps are offset below the hinge linesbetween said length walls and their bottom end flaps.
 10. A collapsiblebox as set forth in claim 9 in which said offset is approximately equalto one or two times the thickness of said corrugated plastic.
 11. Acollapsible box as set forth in claim 1 in which said bottom end flapscomprise an automatic lock bottom.
 12. A collapsible box as set forth inclaim 11 in which said side walls include two length walls and two widthwalls, and said automatic lock bottom comprises each of said bottomflaps on said width walls being hingedly connected to one of said bottomflaps on said length walls along hinge lines that bisect the cornersbetween said bottom flaps.
 13. A collapsible box as set forth in claim12 in which said bottom flaps are adhesively connected.
 14. Acollapsible box made of corrugated plastic comprising: two verticalwidth walls; two vertical length walls; a bottom width flap attached toeach said width wall through a hinge line; a bottom end flap attached toeach said length wall through a hinge line; one of said bottom end flapshingedly connected to one of said width flaps along a diagonal hingeline and the other said bottom end flap hingedly connected to the othersaid width flap along a diagonal hinge line to form an automatic lockbottom to said box; and said hinge lines between each of said widthwalls and their respective width flaps and between each of said endwalls and their respective end flaps comprising a crushed score line anda perforated score line which is substantially parallel to said crushedscore line.
 15. A box as set forth in claim 14 in which said score linesbetween said width walls and said width flaps being offset slightlybelow said score lines between said length walls and said flaps on saidlength walls.
 16. A collapsible box as set forth in claim 14 whichincludes a hand hold in each of said vertical width walls and each handhold comprises a cut line through said corrugated plastic defining ahinged flap depending from a hinge line.
 17. A collapsible box as setforth in claim 16 in which said cut line terminates in a rounded corneron both ends of said hinge line from which said flap depends.
 18. Acollapsible box as set forth in claim 14 which includes vertical hingelines between each width wall and each length wall and said verticalhinge lines terminate short of the top and bottom of said walls.
 19. Acollapsible box as set forth in claim 14 in which said hinge linesbetween said width walls and their respective width flaps and saidlength walls and their respective width flaps all terminate short of thesides of said walls on both ends of each said hinge line.
 20. Acollapsible box as set forth in claim 19 in which said hinge lines allterminate approximately one inch short of the sides of said walls onboth ends of each said hinge line.
 21. A collapsible box made ofcorrugated plastic comprising at least four vertical side walls and abottom end flap integrally connected to each of said side walls througha hinge formed by a score line in said corrugated plastic, said scorelines terminating short of the edges of said end flaps to reducepossible risk of tearing the corrugated plastic.
 22. A collapsible boxas set forth in claim 21 that includes a top end flap integrallyconnected to each of said side walls through a hinge formed by a scoreline in said corrugated plastic.
 23. A collapsible box as set forth inclaim 21 in which said side walls are connected to each other through ahinge formed by a score line in the plastic and said score linesterminate short of the tops and bottoms of said side walls to reducepossible risk of tearing the corrugated plastic.
 24. A collapsible boxas set forth in claim 21 in which said side walls of the box comprisestwo length walls and two width walls having less horizontal extent thansaid length walls, and said hinge between the width walls and theirbottom end flaps is offset downwardly from said hinge between saidlength walls and their bottom end flaps.
 25. A box as set forth in claim21 which includes hand holds in two opposing side walls with a cut linealong three sides of each said hand hold, and said cut line terminatesin a rounded corner at the top of each side of the hand hold.
 26. A boxas set forth in claim 21 in which said bottom end flaps form anautomatically lockable bottom end closure for the box.
 27. A collapsiblebox made of corrugated plastic comprising at least four vertical sidewalls separated by vertical hinge lines therebetween formed by scorelines in the corrugated plastic and a bottom end flap integrallyconnected to each of said side walls through a hinge therebetween, saidscore lines forming said vertical hinge lines stopping short of the topand bottom of said side walls to reduce possible risk of tearing theplastic along the score lines.
 28. A collapsible box as set forth inclaim 27 that includes an automatically lockable bottom end closure. 29.A collapsible box as set forth in claim 27 that includes hand holds intwo opposing side walls, with each said hand hold being defined by a cutline along the bottom and both sides of said hand hold and said cut lineterminates in a rounded corner of the top of the hand hold on both sidesof the hand hold.
 30. A collapsible box as set forth in claim 27 inwhich the hinge line between said side walls and said bottom end flapscomprises two parallel score lines.
 31. A collapsible box as set forthin claim 30 in which one of said parallel score lines is a perforatedscore and the other is a crushed score.
 32. A collapsible box as setforth in claim 31 in which said crushed score is below said perforatedscore.
 33. A collapsible box as set forth in claim 32 in which saidcrushed score is in the interior face of the side wall and saidperforated score is in the exterior face of the side wall.
 34. Acollapsible box made of corrugated plastic comprising at least fourvertical side walls and a bottom end flap integrally connected to eachof said side walls through a hinge line, and a hand hold cut into atleast one of said side walls, said hand hold comprising a cut linethrough said corrugated plastic to define a hinged flap in the side wallwith said cut line on both sides and the bottom of the flap and endingin a rounded corner at the top of each side of said flap.
 35. Acollapsible box as set forth in claim 34 which has at least two of saidhand holds, and said two hand holds are in opposite side walls of thebox.
 36. A collapsible box as set forth in claim 35 in which said hingeline for each hand hold comprises a score line.